FEBRUARY 26, 1925
LIGHT PLANE
THE new de Havilland " Moth " made its first flight last
Sunday afternoon, and, although the flight was only a com-
paratively short one, the machine was found to be in perfect
trim, handle easily and smoothly, and, last but not least,
appeared to exceed the estimated performance at both ends
of the scale. The top speed was above 90 m.p.h., and the
landing speed about 37 m.p.h. The " Cirrus " engine ran
perfectly, and altogether the first flight gave great promise.
It is of interest to mention that Capt. de Havilland himself
tested the machine—a fact which should certainly help to
inspire confidence. Next week we hope to have something
more to say about the D.H.60 " Moth." In the meantime.
an illustrated description of the " Cirrus " engine will be
found in this issue of FLIGHT.
* * *
WITH the advent of the " Cirrus " engine, and the present
tendency to regard some HO h.p. or so as permissible for a light
'plane, there seems to be an excellent opportunity for reviving
the famous Avro " Baby." In the single-seater form this
machine flew, it will be remembered, from London to Turin
without landing, piloted by Bert Hinkler. In Australia
Hinkler also made iong flights, so that the reliability of the
Green engine seems to have been established. That the
engine is perfect will hardly be claimed for a design some
13 or 14 years old, but it would appear that such changes as
seem to be required are not very extensive, and certainly not
radical, so that perhaps we may also see the " Evergreen "
getting a new lease of life. The question of water-cooling or
air-cooling for light plane engines does not yet appear to have
been settled, so that then- is still an opportunity for the former.
* * «
WE are living at a critical time, so far as light 'planes are
concerned, at any rate. The fate of the light 'plane is very
much in the balance at the present moment, and a great
deal mav, and probably will, depend upon the decisions made
during the next few weeks. From the somewhat optimistic
times of 1923, when there was a widespread idea that the
era of the " flying nintor-cyclc " had arrived, we have passed
through the stage of two-seaters with relatively smaller
power, and it would appear that informed opinion is now
rather abandoning the idea of the ultra low-power machine
and turning to something round about 60 h.p. for two-
seaters.
* * *
THE fact (if it be a facti is to be regretted in many ways.
and we personally are not yet convinced that the jump from
1,100 c.c. to 4,500 c.c. is really required. On the other hand,
the Lvmpne engines of last year were giving, on an average,
something like 34 h.p. for 1.100 c.c. capacity, and so the
increase in actual power is not so great as the sudden jump
in cubic capacity would indicate. We do think that an
increase in power was required, and as the plans for this year
are to abandon capacity restrictions altogether, the jump
from 34 to 65 h.p. may be justified. In the case of the
" Cirrus " engine there was already a larger type in existence,
whose cylinders, pistons and crankshaft could be utilised,
and doubtless this is one of the reasons for the somewhat
large capacity of 4i litres. And it should be remembered
that at the moment the demand for light 'plane engines cannot
be expected to be a large one, and that therefore the produc-
tion of a low-price engine, even if somewhat on the large
side, may be expected to balance the slight disadvantage
of an engine somewhat large for the job.
• * *
THERE is another point which is, perhaps, apt to be lost
sight of, and that is that we have hitherto been in the habit
of thinking of the light "plane as one single type. Now there
is really no reason why that should be so. On the contrary,
even in the light 'plane class it seems reasonable to suppose
there will be a number of types, such as the school machine,
the touring machine for the private owner, the sporting
machine with, possibly, light construction and a high-efficiency
engine, and the racing type. There should, among all those
types be plenty of room for the low-price, somewhat large,
but very robust machine and engine, just as there will be
room for the more refined racing type. After all, to take an
instance from the automobile world, light cars are of many
types and of many qualities and prices without ceasing to
be light cars. Why should not the same apply to light
aeroplanes ? From "this point of view, therefore, we welcome
the production of the " Cirrus " engine and the De Havilland
" Moth," both of which should fill a very useful gap and
should do much to get sporting flying re-established on asound basis.
* * *
IN fact, we may look forward to the day when there arelow-power aeroplanes, light planes, lighter 'planes, and
slightly slighter 'planes ! The one great thing achieved atthe moment is that we have got away from the capacity
rating, and that some other figure, probably the total weight,will form the basis of the future light aeroplane as a class.
* * *
THE paper by Col. Fell on light 'plane engines, reportedelsewhere in this issue, came at a very opportune moment,
and the discussion which followed it showed the trend ofmodern opinion. Most of the various points raised by
Col. Fell were dealt with during the discussion, but there areone or two to which we should also like to draw attention
here.
* * *
ONE sentence in Col. FeU's paper seems open to challenge.
He said (after having stated that " the public and even aircraft
designers have been misled as to the t\*pe of engine that is
required by statements made in the non-technical and semi-
technical press, to the effect that it is possible to fly an aero-
plane satisfactorily with a motor-cycle engine ") : " At this
stage it is desired to state quite definitely that this is
impossible." Col. Fell promised figures to back up his
statement, but failed to give them. Now this statement
should not be allowed to pass unchallenged. To begin with,
on whose authority is it desired " to state definitely that this
is impossible " ? And in what sense is it impossible ? We
do not think Col. F'ell can have seen Longton flying the English
Electric Co.'s " Wren " with 400 c.c. A.B.C. motor-cycle
engine at Lympne in 1923, otherwise he would not have
made such a sweeping statement. In point of fact, the
Wren " had approximately the same performance as a
Maurice Farrnan " Shorthorn " ; she was remarkably stable
and, in spite of her very light wing loading, was but little
affected by gusts. Longton's " crazy flying " on her was a
wonder to behold, and certainly the machine was not under-
powered.
* * *
IF Col. Fell refers to two-seaters, we would call his attention
to the performance curves of the Beardmore " Wee Bee " of
last year (published in FLIGHT of September 25, 1924).
These curves (which have, incidentally, been substantiated
by the machine's actual performances) indicate that the power
reserve is a considerably greater percentage than that of the
majority of commercial aeroplanes. Apart from the fact
that the " Cherub " is not a motor-cycle engine, although it is,
presumably, among those which Col. Fell considers as such,
there is thus no difficulty in disproving what can only be
described as a far too sweeping statement. If Col. Fell had
qualified his statement by saying that it was impossible to
fly with such engines in machines that could be commercially
produced, few would probably have disagreed, but technically
there is nothing at all impossible in flying with a motor-cycle
engine (or was not until the Technical Department started to
insist on changes and additions in certain machines, which
resulted in the engines having to be " faked " also). And, on
the whole, the motor-cycle engines behaved remarkably well,
and many machines put up very creditable performances, such
as Hinkler's 1,000 miles without a forced landing.
* * *
F'OR the first time in history the Air Estimates, recently
issued, contain an item referring to light 'planes. This is
subhead F.2 under Vote 8 (Civil Aviation), and laconically
reads : " Assistance to Light Aeroplane Clubs, £22,000." In
his memorandum on the Air Estimates. Sir Samuel Hoare
merely states : "A sum is also included for the first time this
year to assist in the establishment and maintenance of a
limited number of light aeroplane clubs. The details of the
scheme are still under discussion."
* * *
IT may be recollected that the original scheme included the
grant to each of ten clubs of an annual subsidy of £2.000, but
that number of clubs has been reduced to six for the present
In view of the fact that the offer of £2,000 was. on closer
examination, found to be inadequate, the total to be voted does
not appear any too large, but if the number is, for the present,
to be restricted to six (not that we necessarily agree that this
number is sufficient), there should be a possibility of getting
started in real earnest, with a reasonable amount of financial
assistance for each of the six.
Ill